SiC is a very stable material. It is difficult to control a SiC surface for suitably growing crystal in an ordinary III nitride crystal growth apparatus. For this reason, the steps as follows have been performed. Under the heat treatment of HCl gas, a step-terrace structure is formed on the surface of the SiC substrate 1. By performing chemical treatment on the surface of the SiC substrate with aqua regia, hydrochloric acid and fluoric acid in sequence, and etching the silicon oxide film which is formed on the surface of the SiC substrate, a clean surface 3 of the SiC substrate is formed. Then, the SiC substrate is installed into a high-vacuum apparatus which is kept in ultrahigh-vacuum condition such as 10< SP> -6< /SP> ~10< SP> -8< /SP> Pa. On timing t1, an atomic beam of Ga is applied under ultrahigh vacuum condition and a temperature below 800 DEG C. After that, the substrate is subjected to a heat treatment under a temperature above 800 DEG C. The process of atomic beam application and heat treatment has to be performed more than one time. The growing temperature of A1N film is set, and A1 atom is applied to the surface of SiC substrate under ultrahigh vacuum condition before N atom is supplied.